Yes, Megan Swiftblade is briefly encountered in The Temple Between and noted to be jealous of the PCs' success. I will note that Megan's brief intro description in Siege of Bordrin's Watch doesn't mention this aspect of her personality, but instead emphasizes her protectiveness of her fellow adventurers and her dedication to the protection of innocents. I'll also note that all of the Freeriders have to be in on this secret keeping foolishness, including a dwarven, no-nonsense cleric of a good deity.
In any case, having her be jealous enough to treat the PCs poorly when she's been guarding a site that has been poisoned with many who talk against the party isn't too bad. However, in Beyond the Mottled Tower, she and the Freeriders are noted to have learned that Sarshan was the one supplying mercenaries to General Zithiruun in his attempted conquest of Overlook. They also know Sarshan is going to be using something called blood chaos as retribution against the vale. She and the Freeriders then do not tell anyone else about this. They are then subjected to no fewer than three assassination attempts. They still don't tell anyone about Sarshan or the threat to the vale. The Freeriders decide to split up their party, thinking this would be safer. Through unclear means, Megan communicates with the Overlook authorities to the effect that she'll tell them who was behind the mercenaries in the assault, but only if they agree to protect her.
Megan decides to hide out in her home town. There is an extremely violent catastrophe in her village that threatens numerous innocents, involving something that could reasonably be called blood chaos. Megan is hurt, forced out of hiding, her home village badly threatened and rescued by the PCs. The PCs then must make several Diplomacy checks to *coax* her into telling them that Sarshan was behind the mercenaries in the General's assault and that he plans to use blood chaos to revenge himself on the vale.
I have a hard time describing the number of things that make the above a complete Idiot Plot. Why don't they tell? This is treason against the Vale! They know about a upcoming plot to harm the people of the Vale *and* a responsible party for an assault on Overlook that claimed the lives of soliders and innocents. If they are jealous of the party, don't *tell* the party. Tell the authorities! Second, they then decide that the best response to three assassination attempts is to separate and hide, rather than simply telling their secret and removing the most probable cause of the assassination attempts. Megan also decides to hide out in her home town. Brilliant. Now she's put innocents in her home town at risk. Third, the secret she's keeping isn't even a good secret! Geez, the party and Council should have guessed that Sarshan was working with the General freaking ages ago! He was gathering mercenaries and sending them into the world back in Umbraforge and he even told the party that they should expect a disaster in the Vale! I can't imagine the laughter and groans around the table:
Megan: My secret? OK, I'll tell you at long last. I've survived assassination attempts, risked my home town, but I've always kept this incredible secret! The person behind the mercenaries was....was...Sarshan!
PCs: Uh....you're joking right? The same Sarshan who's been involved in every darn adventure we've had in this? Of course he was working with the General! Who else? Man, i thought we might get something interesting out of this.
I've gone on more than long enough, so I won't even start in on how stupid this whole adventure makes Sarshan look. (Dude, you haven't got a secret worth keeping and your actions to remain anonymous are moronic.)