No, its not your imagination OP, haste running speed is slower. I was gonna post a thread about this when I got to work, except mine was going to be titled "I would've gotten away with it too if it wasn't for you meddling kids".
This is the very first spell I cast when I logged in and I had to cast it a couple of times just to make sure it had taken. The pendant of time is slower too. Didn't actually test it against my 30% striders though.
Did this come up in Beta at all?
Now I wouldn't mind this so much except that it wasn't announced and theres no reasonable explanation for it (well, actually there is, but its a technical one and I'm gonna let Turbine bring it up).
What I didn't think of doing is buying some haste pots / fast travel pendant from the store and see which is faster. Possibly even take a fraps.