yes it is normal. usually it takes time for babies to get used to tummy time. and sometimes when your baby is trying to master a skill and if they fail they get frustrated and cry. my baby used it do it alot. and now she is trying to crawl and when she isn't able to do it she cries and whines. and physically its quite exerting. so i suggest you let ur baby cry a bit don't pick her up immediately. she will get used to it.