Baby jabs

help! my daughter is 18 weeks and just had her 16 week jabs on Thursday 13, she had her last lot on 15/9. Got home from work to letter saying she's due to have her 16 week jabs on the 27/10 thats in two weeks and she'll be 20 weeks.....I'm panicking that's she's had them too early? she's absolutely fine hardly had any calpol just one dose!! anyone else experienced this ?