Dealing with these parsing errors can be very painful. It seems to me that %F is not being respected. Consider the following:

$ perl -MTime::Piece -le 'print Time::Piece->strptime( "2015-04-28T11:
+33:12", "%Y-%m-%dT%H:%M:%S" )'
Tue Apr 28 11:33:12 2015
$ perl -MTime::Piece -le 'print Time::Piece->strptime( "2015-04-28T11:
+33:12", "%Y-%m-%dT%T" )'
Tue Apr 28 11:33:12 2015
$ perl -MTime::Piece -le 'print Time::Piece->strptime( "2015-04-28T11:
+33:12", "%FT%H:%M:%S" )'
Error parsing time ...
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Why don't you change your format string to "%Y-%m-%dT%T" and see if that works? (It did for me using Time::Piece v1.29.)

L-LL-L--L-LL-L--L-LL-L--
-R--R-RR-R--R-RR-R--R-RR
B--B--B--B--B--B--B--B--
H---H---H---H---H---H---
(the triplet paradiddle with high-hat)