When Did It Change?

It has basically always been the case that I have pronounced the word when as [wɪn], homophonous with the word win rather than as [wɛn] (Incidentally, I also say [wɪnt] not [wɛnt]. I considered the two to be distinct completely, unlike say, lie and lye, which I thought had a phonetic similarity. I didn't even realize that I was doing anything unusual or different from anybody else until somebody didn't understand me one time. I realized that it was in fact true that I pronounced the two the same, and decided eventually to take some pride in it. This all came crashing down the yesterday when I caught myself switching to the ɛ form completely naturally. It had always taken effort to produce the ɛ form and often came out as [ʍɛːn], but this time it was almost as if I had always been using that form, probably from all of the practice I get pointing out the thing that I don't say. I haven't seen any instances of [wɛnt] so far, though I wouldn't consider it to be at all unlikely. Hopefully I can keep my usage of [eʲŋ] in place of what is apparently far more common [æŋ], though it looks like the same kind of thing is happening.