"Banning peer: too many pex messages"

[Guest jariv]

There is a selection from my log (this week):

"

15:13:08] [µTorrent 3.2 (1.2)]: Banning peer: too many pex messages. 5 since 15:13:07

15:46:51] [bitTorrent 7.6.1 (19.6)]: Banning peer: too many pex messages. 5 since 15:46:51

20:00:55] [Azureus 4.7.0.2 (100.0)]: Banning peer: too many pex messages. 5 since 20:00:54

03:31:29] [KTorrent/4.2.0 (100.0)]: Banning peer: too many pex messages. 5 since 03:31:29

"

Were current clients supposed comply with "once per minute" rate?

Ps. Is pex a four letter word? (in forum searches that is)