rxxr2 doesn't detect /^a*b?a*x$/

[dimaqq]

I've ran rxxr and rxxr2 on ReDoS examples from Wikipedia, and it detects most but not all evil regular expressions:

/^(a+)+$/ detected, pumpable aa
/^(a|aa)+$/ detected, pumpable aa
/^a*b?a*x$/ not detected

While of course, long sequence of a is equally deadly for the last expression.