El Mahdi
Muad'Dib of the Anauroch
[MENTION=6677945]SnowleopardVK[/MENTION] I think you're well within your rights to run it this way, I run it this way, and every DM/GM I've ever played with has done the same thing.
But, if you're group has a problem with this, then just revert to the rules. Both the 3.xE and 4E DM Guides describe using passive checks for the PC's when you don't want to ask for a skill check (because it might clue them in that something is going on, or you're trying to keep the action moving, etc.). A passive check is essentially the PC's "take 10" score for that skill (this rule is the same in 3E and 4E).
Personally, I'd prefer having you roll since in many situations, a "take 10" score may be an automatic failure...but I might have a chance with the dice. But if you're players don't see it this way, then it's their loss.
But, if you're group has a problem with this, then just revert to the rules. Both the 3.xE and 4E DM Guides describe using passive checks for the PC's when you don't want to ask for a skill check (because it might clue them in that something is going on, or you're trying to keep the action moving, etc.). A passive check is essentially the PC's "take 10" score for that skill (this rule is the same in 3E and 4E).
Personally, I'd prefer having you roll since in many situations, a "take 10" score may be an automatic failure...but I might have a chance with the dice. But if you're players don't see it this way, then it's their loss.