Financing liabilities question - callable bonds

I was going through a problem for recognizing callable debt gain/loss. For example, if rates drop and bond value rises to 105 on a callable bond with call px of 101, the economic gain is 4. However, the accounting loss is 101-100(par value), so 1. I think this is a little bit misleading. Shouldn’t the call px be compared to whatever the book value is? Even though par = 100, if the book value = 98, the loss would then be 3 (101-98). I was slightly confused at first, but this is how Schweser did it in one of their problems. Am I going about this the right way? Thanks.