The "alert" you received likely has nothing to do with your score increase. Alerts are mistaken for the reason for a score change all the time. No doubt you received the alert because a long inactive account became active, which then generated a new score. IMO, your score went up for another reason.
The only way I could possibly see this inactive account possibly raising your score (and this is a stretch) is if it was 1 of exactly 3 credit cards that you had open and if after a period of time an inactive card isn't "seen" by FICO. Then, if out of the other 2 cards you had one with a reported balance and the other at zero, you would have gone from 50% of your cards reporting a balance to 33% of them reporting a balance when the inactive card became active again. Like I said, it's a stretch and that could have only happened if you have exactly 2 other "active" credit cards in addition to the Best Buy card.
As others have started discussing above, things like AAoA, AoYA, inquiries, etc. are things that should be looked at here... basically, different slices of the FICO pie.
