This happened to me. Always had a reasonably good attendance record with maybe one sometimes two absences per year max, no more than a day or two at a time. Genuine reasons for taking them, my rationale was to always try and go in as I was a one man band of sorts, so the longer I was off the more that was waiting for me when I returned.
However one year I was off four times, only a day or so each time, but got pulled in for a meeting with the boss in accordance with company policy. Was advised if off again within that year it would be escalated with HR and would result in a written warning. To be fair my boss was okay about it, however she had to do the meeting to comply with the policy.
One of my colleagues said 'you should just have stayed off for five months, that would have counted as one instance of being absent.'
On the one hand I get the rationale about managers needing to plan resource, plug gaps etc, however on the other hand, depending on the job type, it amuses me that employee A can get pulled in for being off for e.g. 4 x 1 days, however employee B won't be warned for being off for 1 x 20 days.