The problem with trying to infer something without actually directly saying what he means is that it leaves Aziraphale with very little information. Definitely not enough for him to actually pull together any real assumption. They had a lot of conversations in the palace, mostly about explaining Asgard and with a very sizeable side of complaining from Crowley's end.

Along with a few awkward conversations while they laid in bed together and very pointedly didn't discuss that particular topic.

He looks at Crowley carefully, as if he might be able to pull an answer out of what he can glean from his expression. Unfortunately not, so he's forced to simply ask.

"Which one?"