When did you register your account? I have a bronze account too that inactive for a long time. I stop wagering here after I reach the first VIP level which took me so long to meet the xp required.
I just check my email but can’t see anything about this promotion. I think this is just on random basis for users that meet the Stake criteria probably the date of registration of the account and not the VIP level. I will try to become more active here just to try whether I will receive same offer or not. Congrats.
Stake bonuses like monthlies and weeklies increase based on how much you have in your wagering volume but the exact formula is not published, there's some magic to it. I just check my email but can’t see anything about this promotion. I think this is just on random basis for users that meet the Stake criteria probably the date of registration of the account and not the VIP level. I will try to become more active here just to try whether I will receive same offer or not. Congrats.
For bonuses like these not much is known. If there's some downtime or a mistake in Stake they may chose to give back to the community at their own accord. So the $25 given is very generous indeed. I was active wagering this week so surely it must have played some role but otherwise I don't know much. It's just very generous because it's unexpected and they definitely didn't have to give that much.
Maybe I'll do the same later once I reach the next level since I'm now heading to Platinum III, need to wager about $100k for it but I'll just play normally and I wont force myself to deposit more than usual. 
