Recoil spring replacement?

Ruger lists the P345 as having a 12lbs recoil spring (the P90 is 11lbs :0 ). I have heard of people shooting 5000+rounds from a P345 and not mentioning anything about changing or strengthening the recoil spring for +P or the prolonged use. I am kinda worried because I don't want to damage the frame, but I do think the spring is kinda weak (it failed to retutn to battery once during breakin). I would like to find some, but I don't think wolf makes springs for the 345. Will the P90 springs fit a p345? After how many rounds should I replace this weak spring? Should I replace the spring in my sigma (it has 2500rounds on it)?