The problem is that they're both too good for such a long duration. I'd love to see some long-duration spells that boost AC (other than Mage Armor) and hit points (see Andy's spoiler thread - False Life is in the new PHB) rather than ones that make me nearly invincible* to physical combat. That would work great with the shorter term buffs like Mirror Image
I personally have only had trouble with Teleport being used to avoid encounters once. I used a frustrating monster (the new bone devil) and so the players teleported back home. Fortunately, they don't pull the "kill one monster, go home and rest, then go back next day with full spells" cheese, but it's still possible under the rules.
* IME most opponents have both ranged and melee weapons, but their ranged weapons are usually much weaker than their melee weapons (eg lower attack bonus, lower damage, and so forth). On the other hand, flying opponents are just nasty, since they can usually out-fly me