Haven't been to Tahoe myself but I've been collecting accounts from that whole Sierra Nevada region for about three years now and there's something going on out there that doesn't get talked about enough. The altitude, the water, the geography - something about that combination seems to attract activity.
What specifically did you see? Shape, movement pattern, any sound or complete silence? The silence thing is often what gets overlooked but its one of the more consistent details across credible reports.
I do EVP work primarily but I've started crossreferencing craft sightings with locations where the audio anomalies are strongest and the Sierra Nevada comes up more than you'd expect. Not saying theres a connection, just that the overlap is interesting.
You're definitely not losing your mind, or if you are then there's a lot of us in the same boat. Post whatever details you can remember, even the stuff that seems too weird or small to mention - those details are usually the most useful.