Without taking the finished quilt top apart!

I was doing the last side sash on my quilt and when I was pressing the seams I noticed one of the seams is soooo short it is literally being held together by several thread widths!

I found another one earlier in the piecing process and was able to just resew it. But now the whole thing is together how do I fix it with out undoing a good portion of my quilt top or leaving it puckered?

I am so annoyed at myself but I had a look at the rest and thankfully haven't found any other mistakes like that...

Over all I am please since it is only my second quilt and I have learned new things...so fixing a poor seam allowance is going to be another...lol live and learn..

Cheers
Julie
Need it fixed before class so I don't look stupid for such a simple mistake..:-D