I wasn't tracking my balance that closely and I was out of the city for about 10 days, returning Monday when I got the "see agent" message at the turnstyle.
Just checked my account, and while I had 2 rides post on 5/30, I only had 1 ride post on 5/31 (for a 5/30 swipe, which is when I left town) that took me to a -$1.35 balance (and I'm now in "revoked" status), so I definitely didn't maximize my usage here!

In other news, my Wage Works transit card in my Apple Wallet is working fine! It's a bit of an adjustment to not go for my wallet at the station, lol (though I do use the Apple transit express in London as I'm there often).