Most certainly get it re-biased. An Amp Tech will not charge a lot for this, and it's well worth it for max tone and max tube life. In the future, buy a Quad of matched power tubes, and get the one set biased, the second back up set will slide right in as the replacement no issues or need to re-bias again. Then, repeat the Quad matched purchase thing again when that last set of quad matched tubes finally quits.
Yup, especially with the inconsistency of modern tubes, you should check the bias any time you replace power or rectifier tubes. Once you determine the 70% dissipation point, use your ears for setting the bias for the best sound but not to exceed the 70% point.
If it had Grovetubes in it, you should be fine, mesa and Grovetubes use the same rating system to grade their tubes. But like said having it checked is not a bad idea and learning to do it is even better