Ripnugget & Stickfoot difficulty modifier persists until end of turn

When a character fails the Stealth check before encountering Ripnugget & Stickfoot, the +2 difficulty modifier affects all checks until the end of their turn, not just the second combat check as stated on the card. For example, after defeating the encounter, Kyra tried to recharge her Aid spell and faced a DC of 10 instead of the normal 8; likewise for recharging the Cure she cast right before ending her turn. The difficulty modifier disappeared at the start of the next character's turn, fortunately.

This is on normal difficulty so there are no other modifiers in play.