As far as I remember, yes. But I am always happy to say "I was wrong"
I haven't gone through all of these, but according to
this, R' Moshe speaks about the pill in EH 4:74(2), 1:65, 2:17, and 4:72 (the article mentions one other tshuva without sourcing it). The article presents R' Moshe as having had an evolving shittah on the pill, leading more and more l'tzad issur.