The sabre cat is supposed to ambush the travelers unexpectedly in Skyrim - even on the safest roads - so yes,it's normal (even if "4 in a row" seems a little exaggerated to me,i must admit)
Slightly OT, but I can believe the 4 saber cats in a row for a couple of different reasons. I always seem to key into the 'paired saber cats' random encounter around levels 8-10. Not sure if this is the 'old orc' encounter where he got his death. But, literally, if I want some saber cat skins, I only need to go towards Helgen around those levels.
2nd reason I can believe it has to do with the system. I'm PS3, but this might also apply to the OP. I was fishing for a Solitude job from Delvin so I could finish up that part of the Thieves Guild and, rather than getting some failed quests by turning them down after I found out where they were (discovered this went onto the stat sheet when I saw I had -14 quests completed for the TG), I kept reloading if it wasn't the job I wanted. Needless to say, it took a while. Headed out of Riften, ran past the Guard Tower for the little dirt road around that bandit keep and I found my level 22 character facing 4 cave bears chasing a single deer. Think I saw a similar thing with another character on the 1st College quest. After fishing for a spell I would actually use (my paladin had no use for a flame atronach spell) in the initiation, I headed over to Saarthal and found myself against 3 frost trolls and a pair of spriggins. Anyway, that might be a possibility for why you saw some many in a row.
Best advice from my thief/ranger is to sneak even along the road. Sneak was my first skill to hit 100 and, not so coincidentally, smithing was the second (from making use of all those wolf, bear and saber cat pelts found on journeys).