Having to have 2nd 20 week scan

We had our 20 week scan and baby was in a really awkward position (head super far down), refusing to budge so they gave up on checking the head and brain and told me to come back in 2 weeks.

Everything else was fine but I'm now so worried there's something wrong - is it usually so long after the 1st attempt that they suggest a second one? Initially the sonographer even said come back in 3 weeks, it just so happened I wasn't available so they looked the week before. Has anyone else had a similar experience?