Most likely it's just a stroke of bad luck and otherwise spam results.
To become an UltraPeer you need at least a decent connection and also need a way through the firewall i.e. accepting incoming connections. This isn't needed to just share files. So if you are firewalled and the user whose search result you pick is also firewalled, then you will in many cases have at least a bit of trouble connecting, no matter what Limewire in the past has claimed.
If you can download fast from the Ultrapeers it at least completely eliminates any suspicions in regards to your ISP doing any trotling or blocking to your connection.