Is yeast still good?

I made a Sweetwater IPA wannabee a month or so ago with Denny’s Favorite (Wyeast 1450).  I really like this yeast.  I kegged it about two weeks ago, but left it and about a half gallon of beer in the fermenter.  It’s been setting in my house since.  Is the yeast still viable to use for a beer I plan to brew next week?  The temperature hasn’t gotten above 80F, but are such high temperatures bad for the leftover yeast? Opinions are welcome!  ;D

Try feeding it up or making a starter to see how viable it is.
Normally, it’s better to decant the yeast and some of its beer to a flask or a jar and store it in the fridge.  Doing that, I’ve used a recycled slurry as much as 6 weeks later (though for me 3 is more typical).  In any case, next time, keep it in the fridge.