Even if you seperate the parts glued together with 5 min. epoxy, you would never be able to remove the 5 min. epoxy from the parts epoxied. There would always be a layer of 5 min. epoxy sealing and seperating the 30 min. from the wood in the joint. In my opinion, this process would likely decrease the strength of the second glue job to less then the initial 5 min. epoxy bond.

gboulton is certainly entitled to his opinion. However, I would not hesitate to fly the plane as is and wouldn't worry about the strength of the 5 min. epoxy bond one bit.