No. This is likely caused by by either the upgraded iceweasel and/or torsocks package in Debian wheezy. If I was into betting, I guess it would also happen on plain Debian. For example torsocks + iceweasel. So this is likely not an uwt issue. You can test that. And if that’s a problem, you can report his issue upstream against torsocks.
It’s unknown to me if torsocks is leak proof solution to torify iceweasel anyhow. [In case of Whonix, it wouldn’t leak through clearnet, but through Tor’s TransPort. But still. This is what you wanted to avoid, no.]
You’re better off not using stream isolation rather than downgrading. Staying with wheezy which gets much less attention nowadays is a much bigger security issue than non-perfect stream isolation. Iceweasel is discouraged anyhow, but you probably know this already.