My guess would be that CentOS is sending you a colourized or otherwise escape-sequence-mangled prompt, but it's hard to tell.

Have you tried using wireshark to see what's actually being sent over the wire, to make sure the prompt you expect is what you're sent? Just using 'telnet' isn't really enough, since you might not be able to see anything that's not printable. (Edit: Actually, as suggested below, use the dump_log option - it sounds much simpler than wireshark).