I had a fall on my mountain bike recently and landed on my hip. The region is now still swollen and is quite hard. Is this cause for concern?

Could be. since if hjip joint could slow blood flow if hard and swollen alot , should go to porthopedic or er for xray and possible mri , use ice pack.
Likely hematoma . It is likely a hematoma, which is a area of bleeding that can occur secondary to
Injury and other causes, when it forms a clit it hardens. I do think it would be good to be seen to verify the diagnosis and to rule out an associated fracture.
Hematoma. With the trauma as described would be concerned about a possible hematoma you should seek an evaluation.
Trochanteric. Bursitis . I believe a steroid shot would improve you greatly! I am a heavy duty mountain biker. It happens frequently with your fall!