Just because you have a T1 doesn't mean you'll become an ultrapeer. You might be firewalled, for example. Or you might have found another ultrapeer that doesn't have enough leaves, turning you into a leaf. LimeWire tries to be a leaf whenever possible.

What we're hearing is that some people get less than desirable search results in leaf mode. You can disable this if you really want by modifying limewire.props as described above.