It was a practice, but it was obviously not well-established. For the next 800 years, Popes were emphasizing continence and celibacy for priests precisely because these were not being observed. It was not until Gregory (I forget which number) invalidated the attempted marriages of clerics that mandatory celibacy was universally observed in the Latin Rite.
Well, yes and no. The fact that the Synod of Trullo saw a need to legislate permission for married men to be ordained while still requiring their abstinence when "handling sacred things" indicates that the practice was well established. That the bishop of Rome refused to ratify the change in discipline also indicates that it was deeply engrained. (Rejection of Trullo was a major element in growing divergence between East and West, exacerbated in the 700s by the Iconoclasm controversy.)
One must beware of concluding from efforts to crack down on violators of a law that violations are widespread. At various times and various places between the 300s and the 1000s (you are referring to Gregory VII), married priests, concubinate priests were more or less common and efforts to enforce celibacy varied as well.
Since the attack on clerical celibacy in the Protestant Reformation, a powerful motive to exaggerate the degree of clerical concubinage has existed for Western Enlightenment/Protestant historians, who have dominated the universities in northern Europe for centuries. I do not wish to underestimate the degree to which the ancient expectation that even married priests must abstain was flouted, but the fact that it persisted over the first 1000 years speaks for its having been deeply embedded.
It's not entirely unlike the priest homosexual scandals: if you read the MSM you have the impression that at least half the priests molest little girls when in fact its a small percent molesting boys. I'm _not_ justifying these actions at all, but do notice how people with axes to grind (MSM today; Enlightenment polemicists or Reformation polemicists of the past) tend to exaggerate how widespread is the practice they are criticizing.