Not only did Kase and Yui finally get to spend some alone time together on this vacation (for Yui... work/club event for Kase), but in a few short sentences, with the only real question Yui brought up being the one about working at a store back in their home town, Kase managed to clear up all of the misunderstandings from overheard conversations and lingering jealousy about her roommate knowing things about her girlfriend that she doesn't.
I'd be willing to bet that Kase mentioned the possibility of working at the store in their home town with the thought in mind that Yui might want to live near her parents, but, since they're still keeping their relationship on the down-low, she didn't want to say, 'but I'd be happy to live anywhere that my girlfriend wants to move." And now that Yui knows that the REAL reason she uses that sunscreen is that it reminds her of the smell of Yui's hair, she knows that Kase's roommate might know what brand Kase likes, but has no idea why she likes it.
I still think that the roommate is going to be a complication somewhere along the line, though not as an ACTUAL romantic rival. I think she'll make a move on Kase at some point.